A lead-acid battery used in an automobile or the like has, for suppressing rising of an internal pressure of the battery, a structure for discharging a gas generated in a container from an exhaust port. For example, in Japanese patent No. 5521390 (patent literature 1) and JP-A-2014-107262 (patent literature 2), a lid member which seals a container has the double lid structure formed of a middle lid and an upper lid, and an exhaust passage is formed between both lids. A bottom surface of the exhaust passage is inclined downward toward a return flow hole which is communicated with the inside of the container so that solution droplets in the exhaust passage returns to the inside of the container from the return flow hole while moving along the inclined bottom surface.